Workpiece support structures and apparatus for accessing same

ABSTRACT

A workpiece container stores at least one workpiece having a bottom surface and a peripheral edge. In one embodiment, a workpiece support structure is located within the container enclosure, which forms multiple vertically stacked storage shelves within the enclosure. Each storage shelf includes, in one embodiment, a first tine and a second tine for supporting the workpiece in a substantially horizontal orientation. The bottom surface and peripheral edge of a workpiece seated on a storage shelf extends beyond the outer edge of both the first tine and the second tine. An end effector may engage these extended portions or “grip zones” of the workpiece.

CLAIM OF PRIORITY

This application is a continuation of and claims priority, under 35 USC§ 120, to U.S. patent application Ser. No. 14/452,490, filed on Aug. 5,2014, and entitled “Workpiece Support Structures and Apparatus forAccessing Same”, which is a continuation of and claims priority, under35 USC § 120, to U.S. patent application Ser. No. 13/337,028, filed onDec. 23, 2011, issued as U.S. Pat. No. 8,800,774 on Aug. 12, 2014, andentitled “Workpiece Support Structures and Apparatus for AccessingSame”, which is a continuation of and claims priority, under 35 USC §120, to U.S. patent application Ser. No. 11/483,366, filed on Jul. 7,2006, and entitled “Workpiece Support Structures and Apparatus forAccessing Same”, which claims priority, under 35 U.S.C. § 119(e), toU.S. Provisional Patent Application No. 60/697,528, entitled “EndEffector Tine and Transfer Methods,” which was filed on Jul. 8, 2005,all of which are incorporated herein by reference herein in theirentirety.

FIELD

The present disclosure generally comprises workpiece support structuresand a workpiece transfer apparatus for accessing the workpieces storedin the structures. More specifically, the present disclosure comprises astructure for supporting the workpieces such that the transfer devicemay randomly access any of the workpieces stored in the carrier.

BACKGROUND

Conventional wafer containers, such as a Front Opening Unified Pod(FOUP) or a Standard Mechanical Interface (SMIF) pod, often containshelves of fixed-pitch spacing to support the semiconductor wafers. FIG.1 illustrates one embodiment of a conventional FOUP 10. The FOUP 10includes a housing or shell 12 and a FOUP door 14 that mechanicallycouples with the FOUP shell 12. The housing 12, which includes a top 18,a back 20, a first side 22, a second side 24 and a bottom 26, defines anenclosure 28. The enclosure includes a support 30 located on theinterior surface 32 of the first side 22 and the interior surface (notshown) of the second side 24. Each support 30 includes multiple shelves16. Each slot between a pair of shelves 16 stores a single wafer. Eachsupport 30 covers a portion of the wafer's peripheral edge while thewafer is seated in the FOUP 10. Access to the outside edge of the waferis blocked by the shelf structure. Wafers are therefore typicallyhandled by thin-bladed end effectors that must reach between adjacentwafers and subsequently either secure the wafer with a vacuum chuck orsome type of edge support and/or gripping arrangement. These methods ofsecuring the wafer often support the wafer by the wafer's back and frontedges or elsewhere on the back edges.

This conventional wafer securing approach has been in widespread use inthe semiconductor manufacturing industry for over twenty-five years. Butthis approach has a number of shortcomings that become more serious asthe wafer size becomes larger. Also, increasing use is being made ofthinned wafers, which are prone to significant bending deflections whensupported by the edge.

Some of the deficiencies of conventional wafer support and carrierarchitectures include:

1) Wafer Mapping—Break-the-beam mapping has proven to be the mostreliable method of determining a wafer's presence or absence and itsvertical position within the container. However, break-the-beam mappingwith the 300 mm FOUP architecture requires expensive and complexmechanisms to position sensing elements into the container.

2) End effector blade travel zone—To access a wafer, the end effectorblade must first travel between adjacent wafers until it reaches adesired position, and at that position, lift the wafer from the supportshelf. As wafer diameter increases, the mass of the wafer and the bladelength required to support the wafer also increases. To maintainreasonable deflection characteristics of the end effector for largerdiameter wafers, the end effector blade must be thicker. If thethickness of the end effector blade increases, the pitch between thewafers must also increase to allow the thicker end effector to passbetween wafers without contacting the wafers. Either container size willhave to increase or fewer wafers can be stored in conventionalcontainers. Additionally, the extra travel length of the end effector issubject to wafer bow, distortion and warping, as well as the vibrationcharacteristics of the end effector due to the rapid horizontal andvertical motions required for time efficient wafer handling. All of thismust be accomplished without any accidental contact between a moving endeffector and a wafer. Contact between the end effector and a wafer willlikely to cause serious damage to sensitive circuits on the wafer aswell as generating particle bursts that may contaminate all the otherwafers in the container.

3) End effector travel path efficiency—A conventional end effectorplaces a wafer in a container and then withdraws to enable verticalmotion clearance for randomly accessing the next wafer, which is thenwithdrawn and taken to a process or metrology location. Thus, fourhorizontal moves are required for each wafer exchange at the container.

4) Process/Metrology chuck complexity—Typically, wafers are placed onflat chucks or platens for processing or measurement. In manyapplications, the wafer is secured to the chuck (and planarized) byapplying vacuum. Use of conventional vacuum or edge grip end effectorsnecessitates large cutaway areas in the chuck to enable release of thewafer and withdrawal of the end effector blade.

5) Multiple wafer handling—It is very difficult in today's architectureto pick or place multiple wafers simultaneously or to enable individualselection of desired wafers in a mass transfer mode.

Thus, it would be advantageous to have an end effector with thesefeatures. The various embodiments of an end effector and a tinestructure described herein provide such features.

SUMMARY OF THE INVENTION

One aspect of the present disclosure is to provide a new apparatus forsupporting semiconductor wafers or substrates. In one embodiment, thepresent disclosure comprises a structure that enables storage andtransport of one or more wafers as well as random access pick and placehandling of individual wafers or groups of wafers.

Another aspect of the present disclosure is to provide a tine structurethat supports each wafer by a pair of cantilevered structures. In oneembodiment, the pair of cantilevered structures each includes twocontact surfaces for supporting the wafer; one contact surface at thedistal end and the other contact surface at the proximal end. While awafer is seated on the cantilever structures, the peripheral edge of thewafer is exposed or accessible by an end effector. A portion of thewafer's bottom surface is also exposed or accessible by an end effector,and in one embodiment is referred to as a “grip zone.” In anotherembodiment, each cantilever structure includes a third contact surface.

Yet another aspect of the present disclosure is to provide a tinestructure whereby an end effector may travel along the outside of thesupport structure between wafers. In one embodiment, the pair ofcantilevered structures are spaced apart such that a portion of a wafer,seated on the cantilever structures, extends out beyond the outer edgeof each cantilever structure. An end effector according to the presentdisclosure may then travel between wafers along the outside of eachwafer; eliminating the need to travel across the entire wafer surfacesimply to lift a wafer off the support shelves. In one embodiment, theend effector travels along the outside of the wafer until the endeffector is at a height whereby the end effector arms can be positionedunderneath the wafer. This distance, by way of example only, comprises afew millimeters, and does not require the end effector to travel acrossthe wafer surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a perspective view of a FOUP, according to the priorart;

FIGS. 2A-2B provide a cross-sectional plan view and a side elevationview of an embodiment of the present disclosure;

FIG. 3 provides a plan view of another embodiment of the presentdisclosure;

FIG. 4 provides a perspective view of another embodiment of the presentdisclosure;

FIG. 5 provides a perspective view of yet another embodiment of thepresent disclosure;

FIG. 6 provides a perspective view of still another embodiment of thepresent disclosure;

FIG. 7 provides a perspective view of another embodiment of the presentdisclosure;

FIG. 8 provides a perspective view of yet another embodiment of thepresent disclosure;

FIG. 9 provides a plan view of yet another embodiment of the presentdisclosure; and

FIG. 10 provides a cross-sectional plan view of the container shown inFIG. 10 in conjunction with one embodiment of an end effector accordingto the present disclosure.

DETAILED DESCRIPTION

For the purposes of describing this invention only, the workpiecesupport structure 102 will be described in reference to a carrier orcontainer. A container or carrier may include, but is not limited to, amoveable, closed or open structure used to hold, store, transport orprotect semiconductor wafers, substrates, flat panel displays and thelike. Such a container includes, but is not limited to, a wafercassette, a Standard Mechanical Interface (SMIF) pod, and a FrontOpening Unified Pod (FOUP). For containers that include mechanicallyopenable doors, the present disclosure may be used in conjunction withfront opening and/or bottom opening containers. Of course, the workpiecesupport structure 102 is not limited to such containers and may be usedin conjunction with any type of workpiece storage needs.

FIGS. 2 and 4-8 illustrate one embodiment of a support structure 102. Inthis embodiment, each support structure 102 includes a base member 104and multiple tines 106. Each tine 106 forms a cantilevered structureextending or projecting from the base member 104. A tine 106 maycomprise any shape including, but not limited to, a flat surface, ashape having a rectangular cross-sectional area, a shape having acircular cross-sectional area, and so on. FIG. 2A illustrates that eachtine 106 is separated by a distance dl, which in a preferred embodiment,comprises 10 mm. The distance dl may comprise other distances as well.There is no ideal distance dl. The distance dl simply must be largeenough such that a wafer W may be vertically lifted off a storage shelf(e.g., tines 106 b 1 and 106 b 2 in FIG. 4) to a height whereby thewafer W may be removed from the storage shelf, and the wafer does notcontact the storage shelf located directly above (e.g., tines 106 a 1and 106 a 2 in FIG. 4).

FIGS. 4-8 illustrate the support structure 102 in use with a bottomopening container. The base member 104 shown in FIG. 4 extends upwardfrom the container door 12. The base member 104 may comprise a structureseparate from the container door 12 or may comprise a structure that ispart of the container door 12.

Any number of tines 106 may extend or project from a base member 104,and the number of tines 106 simply determines how many wafers may bestored in a carrier if the support structure is located within a carrier(each pair of tines 106, or storage shelf, supports a single wafer). Forexample, the wafer supports 102 shown in FIG. 4 each include a basemember 104 and four tines 106. Thus, the support structure 102 shown inFIG. 4 may store up to four wafers W. Each wafer W is supported by apair of tines 106, which may be referred to as a storage shelf. FIG. 4illustrates that the uppermost pair of tines 106 a 1 and 106 a 2 are notoccupied by a wafer; tines 106 b 1 and 106 b 2 are supporting wafer W1;tines 106 c 1 and 106 c 2 are supporting wafer W2; and tines 106 d 1 and106 d 2 are supporting wafer W3. Each pair of tines 106 preferablysupport the wafer W in a substantially horizontal orientation so thatthe wafers W are substantially parallel to each other. FIG. 4 shows thatthe tines 106 are molded into the base member 104. Each tine 106 mayalso comprise a separate component affixed or secured to the base member104.

FIG. 2A illustrates that a tine 106 includes a first end or proximal end112, a second end or distal end 114 and an outer edge 107. If thesupport structure 102 is located within a FOUP, the outer edge 107 ofeach tine 106 faces the interior of the container shell 12 (e.g.,surface 32 of a FOUP side wall 22—as shown in FIG. 1). The tines 106preferably support a wafer W with a minimum amount of contact with thewafer's bottom surface or peripheral edge P. In this embodiment, eachtine 106 contacts or supports the wafer W with only two surfaces—a firstsupport 108 and a second support 110. The first support 108 is locatedat or near the first end 112 of the tine 106. The second support 110 islocated at or near the second end 114 of the tine 106. It is within thescope of the present disclosure for other portions of the tine 106 tocontact the wafer W. In addition, the first and second supports 108 and110 may be located elsewhere along the tine 106. It is also within thescope of the present disclosure for a tine 106 to have only one supportwhile other supports are provided by the base member 104. In a preferredembodiment, each storage shelf includes at least three supports sharedbetween the base member(s) 104 and the two tines 106.

FIG. 2A further illustrates that a tine 106 may also include anadditional support 116. In the FIG. 2A embodiment, a structure 118extends from the tine 106 somewhere between the proximal end 112 and thedistal end 114 of the tine 106. The additional support 116 is preferablylocated at the distal end 119 of the structure 118, but may, of course,be located anywhere along the structure 118. The additional support 116provides an additional support point, and may be desirable when, forexample, the support structure 102 is storing thin wafers.

Unlike the storage shelves in a conventional container, the tine 106supports a wafer, yet enables access to the wafer's perimeter P locatedbetween the two support pads 108 and 110. FIG. 2A shows that the wafer'sperimeter P, and an area 120 of the wafer W, extend out beyond the tine106 between the support pads 108 and 110. The area 120 of the wafer Wthat extends beyond, or overhangs, the tine 106 is referred to as a“grip zone.” The grip zone 120 provides an access area for an endeffector or other mechanical apparatus to contact or grip the wafer Wwhile the wafer W is seated on the pair of tines 106. The grip zone 120is created because the distance d1 between the pair of tines (e.g.,tines 106 a 1 and 106 a 2) is less than the diameter D of the wafer W.Thus, each tine 106 passes under the wafer W.

Accessing wafers stored in a FOUP or SMIF pod with a conventional endeffector requires many complicated, precise movements. First, the endeffector is inserted into the FOUP storage area to a predeterminedposition that aligns the end effector with the wafer it is going toremove from the FOUP. To get to this predetermined position, the endeffector travels between adjacent wafers (e.g., wafers W1 and W2 in FIG.2B) towards the back of the FOUP. The entire time, the end effector iswithin millimeters of the wafer surface. The end effector then rises up;contacting the bottom surface of the wafer, and proceeds to raise upuntil the wafer is lifted completely from the shelf. The end effector,with a wafer seated upon it, is then removed from the container withoutcontacting either of two adjacent shelves or the adjacent wafer. The endeffector operates within this narrow area (e.g., between the twoadjacent shelves) the entire time, and must not damage the wafer (e.g.,contacting either shelf).

A conventional end effector must travel within this narrow area betweenadjacent wafers twice when the end effector drops off a wafer in theFOUP and then immediately travels to another wafer within the FOUP. Forexample, to drop off a wafer within the FOUP, the end effector travelsinto the FOUP and lowers the wafer onto a storage shelf. The endeffector then retracts out of the FOUP; traveling out of the FOUPbetween two adjacent wafers. Once the end effector clears the wafers,the end effector shifts in a vertical direction and is inserted betweentwo different adjacent wafers. The end effector then repeats the samemovements to remove the new wafer from the FOUP. The end effector mayaccidentally strike or contact a wafer and damage the wafer whiletraveling between the wafers.

If the support structures 102 are located in a container (e.g., a FOUP),the present disclosure eliminates the need for an end effector to travelacross the entire face of the wafer simply to position its support padsunder the wafer. At the very least, the end effector has to travelacross only a very small portion of each wafer to position its supportpads. By creating the “grip zones” 120, an end effector may travelvertically within the FOUP enclosure along the outside of the wafer'sperimeter or peripheral edge. When, for example, an end effector reachesthe appropriate height to engage a wafer, the end effector arms onlyhave to move a small distance towards the wafer until the end effector'ssupport pads are positioned to support the wafer and lift the wafer offthe storage shelf. The end effector does not have to travel across theentire face of the wafer to lift the wafer off the support shelf.

FIGS. 2A and 4 illustrate one embodiment of an end effector 200. An endeffector may comprise any structure that acquires, supports andtransports a wafer or any other article (e.g., reticle, FPD, etc.), andis conventionally driven by, or attached to, a robotic mechanism (e.g.,robotic arm). An end effector may passively acquire a wafer (e.g., endeffector include tines) or actively acquire a wafer (e.g., end effectorincludes a gripper mechanism that moves between a wafer loading positionand a wafer contact position). In this embodiment, the end effector 200includes a first arm 202 and a second arm 204. The first arm 202includes a first support pad 210 and second support pad 212. The secondarm 204 includes a first support pad 214 and second support pad 216. Ina preferred embodiment, three or more support pads support a wafer. Forexample, the first arm 202 may have two supports pads and the second arm204 may have one support pad, or vice versa. The first and secondsupport pads 210 and 212 on the first arm 202, and the first and secondsupport pads 214 and 216 on the second arm 204, are spaced apart fromeach other. It is within the scope of the present disclosure for the endeffector 200 to include two or more support pads shared between the twoarms 202 and 204.

The first and second support pads 210 and 212 on the first arm 202, andthe first and second support pads 214 and 216 on the second arm 204, maybe passive supports or active supports. If the supports are passive, thesupport pads 210-216 remain in the position shown in FIG. 4 at alltimes. In this case, a wafer W remains on the support pads 210-216 bygravitational forces. If the support pads 210-216 are active supports,at least one support, and preferably each support, moves between a waferloading position and a wafer gripping position. The wafer loadingposition allows the wafer to be seated on the end effector. After thewafer is seated on the end effector, the support pads moves towards thecenter of the wafer until the support pads contact the peripheral edgeof the wafer.

The configuration of the end effector 200 and the arms 202 and 204 shownin FIGS. 2A and 4 are only for illustration purposes. The end effector200 may have other configurations and the arms 202 and 204 may, forexample, include only one support pad each or incorporate abreak-the-beam sensor system 230. A break-the-beam sensor is knownwithin the semiconductor manufacturing art and is often used toaccurately map the true position of each wafer stored in the containerto provide error-free, scrape-free placement and retrieval of wafers atrandom access positions. Such a sensor system is well known within theart and therefore does not require further disclosure herein.

In effect, the conventional end effector blade is eliminated; the endeffector does not travel within the interstitial spaces between wafers.The arms 202 and 204 of the end effector structure may have anyreasonable thickness as required for minimizing deflection andcontrolling vibration. The support pads 210 and 212 on the first arm 202and the support pads 214 and 216 on the second arm 204 may be passiveretention/support surfaces or activated retention surfaces with motionin the direction 232. If the end effector arms 202 and 204 cannot movein the direction 232, the end effector 200 first travels in thedirection 234 beneath the wafer until the support pads 210, 212, 214 and216 are located substantially underneath the wafer's “grip zone” 120.The end effector 200 then moves vertically (e.g., direction 236 in FIG.2B) to engage the bottom surface 20 of the wafer W and lift the wafer Wa controlled amount off the storage shelf. The end effector 200 can thenwithdraw the wafer W from the container.

If the end effector 200 has arms 202 and 204 that move in the direction232, the end effector 200 can freely travel in the vertical direction236 unimpeded by the presence or absence of wafers stored in thecontainer. In this case, the distance between the arms 202 and 204,while each are located in a retracted position, must be greater than thediameter D of each wafer stored in the container. In operation, the endeffector 200 travels first in the direction 234 until the supports ofeach arm 202 and 204 are substantially vertically aligned with the “gripzone” 120 of a wafer stored in the container. The end effector 200travels in the vertical direction 236 until the arms 202 and 204 arelocated at a desired wafer level. The arms 202 and 204 extend towardsthe wafer until the support pads 210, 212, 214 and 216 are locatedsubstantially in the positions shown in FIG. 1A. The end effector 200moves upward in the vertical direction 236, lifting the wafer W off thetines 106 prior to removing the wafer W from the container in thedirection 234.

FIG. 3 illustrates the end effector 200 shown in FIG. 2A in operationwith a wafer chuck 50. The wafer chuck 50 illustrates that othersemiconductor devices may accommodate the end effector 200. Inparticular, the wafer chuck 50 includes four relief channels 52, 54, 56and 58. Each relief channel is aligned such that the end effector 200may lower the wafer W onto the chuck 50 and no contact the wafer chuck50. Once the wafer W is seated on the chuck 50, the end effector arms202 and 204 move laterally away from the chuck 50 in the direction 232and then retracts from the chuck 50 in the direction 234.

FIGS. 4-8 illustrate various embodiments of an end effector. FIG. 4illustrates one embodiment of an end effector 200 with passive fingers.The end effector 200 includes a body 201 having a first arm 202 and asecond arm 204. The first and second arms 202 and 204 are shown in FIG.4 as curved structures. The body 201 and arms 202 and 204 may havedifferent shapes. The support pads 210, 212, 214 and 216 are each shownhaving a flat contact surface 218 for contacting the bottom surface ofthe wafer and a backstop surface 220 that, in effect, prevents the waferfrom sliding off the contact surface 218. Each support pad may havedifferent shaped contact surfaces that minimize the amount of contactbetween the contact surface 218 and the wafer. The end effector 200 isshown having an optional third finger 220 to provide additional support.The third finger 222 includes a wafer contact surface 224.

In operation, the end effector 200 is positioned such that, when the endeffector 200 moves towards the wafer in direction 234, the fingers 202and 204 move under the grip zone 120 of the wafer to be removed from thecontainer. The end effector 200 moves forward until the contact surfaces218 of the support pads 210, 212, 214 and 216 are located insubstantially the position shown in FIG. 2A. At this point, the endeffector 200 moves upward until the wafer is initially seated on thecontact surfaces 218, and continues to move upward until the wafer israised off the storage shelf (e.g., pair of tines 106). The end effector200 then retracts in the direction 234 until the wafer is removed fromthe container.

FIG. 5 illustrates another embodiment of an end effector 300. The endeffector 300 includes a first arm 302 and a second arm 304. The firstarm 302 has a first support pad 310 and a second support pad 312. Thesecond arm 304 has a first support pad 314 and a second support pad 316.The end effector 300 may also include a third arm 317 having a supportpad 315, which provides additional support.

FIG. 5 illustrates that each arm is pinned to the end effector body 301.The first arm 302 pivots with respect to the end effector body 301 abouta pivot pin 320. The second arm 304 pivots with respect to the endeffector body 301 about a pivot pin 322. Each arm may be affixed to theend effector body 301 by other mechanical devices that allow the arms torotate with respect the end effector body 301. In this embodiment, thefirst arm 302 is rotated about pivot pin 320 by an actuator 324, whilethe second arm 304 is rotated about the pivot pin 322 by an actuator326. FIG. 5 illustrates that the first arm 302 moves between a retractedposition A and a workpiece support position B. The second arm 304 alsomoves between a retracted and workpiece support position.

With the first and second arms 302 and 304 each in a retracted position(e.g., position A), the end effector 300 may travel vertically withinthe container enclosure between wafers because the arms 302 and 304 movebetween the outer edge 107 of each tine 106 and the interior of thecontainer wall. Thus, the end effector 300 moves vertically betweenwafers in the direction 236 without having to move in the direction 234at all—reducing the travel time between wafers. In operation, the endeffector 300 stops at a wafer “pick” location. The arms 302 and 304 moveto position B, which places the support pads 310, 312, 314 and 316underneath the wafer. The end effector 300 rises until the wafer isseated on the support pads, and continues to rise to lift the wafer offthe storage shelf. The end effector 300 then retracts and removes thewafer out of the container enclosure 28.

FIG. 6 illustrates another embodiment of an end effector 400. The endeffector 400 includes a body 401 having a first arm 402 and a second arm404. The first and second arms 402 and 404 are shown in FIG. 6 as curvedstructures. The arms 402 and 404 may have different shapes. The supportpads 410, 412, 414 and 416 are each shown as a cylindrical actuatorhaving a slot 415. The support pads 410-416 may have other shapes. Theend effector 400 is shown having an optional third finger 420 with asupport pad 424 for additional support.

In operation, the end effector 400 moves along directions 434 and 436until the support pads 410-416 are positioned adjacent a wafer W. Atthis point, the support 410-416 move in the direction R1 towards thewafer W until each support pad contacts the peripheral edge of the waferW and effectively grips the wafer. In this embodiment, the wafer'speripheral edge P fits into the slot 415 of each support pad. The endeffector 400 then moves upward along direction 436 to raise the wafer Woff the storage shelf. The end effector 400 then retracts in thedirection 434 until the wafer is removed from the container enclosure.

FIG. 7 illustrates another embodiment of an end effector 500. The endeffector 500 includes a first arm 502 and a second arm 504. The firstarm 502 has a first support pad 510 and a second support pad 512. Thesecond arm 504 has a first support pad 514 and a second support pad 516.

FIG. 7 illustrates that each arm is pinned to the end effector body 501.The first arm 502 pivots with respect to the end effector body 501 abouta pivot pin 520. The second arm 504 pivots with respect to the endeffector body 501 about a pivot pin 522. Each arm may be affixed to thebody 501 by other mechanical devices that allow the arms to rotate withrespect the end effector body 501. The first arm 502 moves between aretracted position A and a workpiece support position B. The second arm504 also moves between a retracted position A and workpiece supportposition B (not shown).

FIG. 8 illustrates an end effector 600. In this embodiment, the endeffector 600 is capable of rotating a wafer seated on the end effector600 about the wafer's center. The end effector 600 includes a first arm602 and a second arm 604. The first arm 602 includes a first support pad610 and a second support pad 612. The second arm 604 includes a firstsupport pad 614 and a second support pad 616. Each support pad, in thisembodiment, comprises a rotatable support mechanism for rotating a waferseated on the end effector 600.

In this embodiment, the first arm 602 is rotatably attached to the endeffector body 601 by a pin 620. The second arm 604 is rotatably attachedto the end effector body 601 by a pin 622. A first actuator 624 rotatesthe first arm 602 about the pin 620. A second actuator 626 rotates thesecond arm 604 about the second pin 622. Thus, the first and second arms602 and 604 rotate between position A and position B. The arms 602 and604 may be rotatably secured to the body 601 in other manners.

It is often necessary to rotate the wafer W about its verticalcenterline axis to read, for example, identification codes or to alignthe geometrical fiducials, including notches, in the wafer perimeter P.The end effector 600 shown in FIG. 8 is only an exemplary embodiment ofan end effector with rotatable support pads 610, 612, 614 and 616 forrotating the wafer W on the end effector 600. Likewise, the mechanismused for reading identifying marks on the top or bottom surfaces of thewafer perimeter can be enabled by utilizing an imaging device (camera)or other reading means mounted on the end effector. Accomplishing this“in-situ” saves time and floor space, and reduces cost and mechanismcomplexity.

The various embodiments of the end effectors described herein allow thearms of the end effector to move vertically external to the wafer'speripheral edge P. Thus, almost all of the wafer support surface of aprocess or metrology tool chuck may be used to support the wafer anddoes not need, in large part, to accommodate the end effector blade(e.g., arms and body). FIG. 3 illustrates one embodiment of a metrologyor process tool chuck 50 in operation with the end effector 200. In thisembodiment, the chuck 50 includes a body 62 having a wafer supportsurface 51, four indentations or channels to accommodate each supportpad, a first slot 60 and a second slot 63. FIG. 3 illustrates a wafer Wseated directly on the surface 51. It is also within the scope of theinvention to have lift pins, or other support structures, extending fromthe surface 51 for supporting the wafer W above the surface 51. Thewafer W may be secured on the support surface 51 (or other supportstructure) by any method known in the art including, but not limited to,vacuum, gravity or electrostatic attraction.

To accommodate the arms 202 and 204 of the end effector 200, the chuckbody 62 includes a recessed area or channel to allow each arm to passthrough the chuck body 62 after the end effector 200 places the wafer onthe surface 51. For example, the chuck body 62 includes a recessedsurface 52 to allow the support pad 214 pass through the chuck body 62,a recessed surface 54 to allow the support pad 216 pass through thechuck body 62, a recessed surface 56 to allow the support pad 212 passthrough the chuck body 62, and a recessed surface 58 to allow thesupport pad 210 pass through the chuck body 62. In operation, the endeffector 200 places the wafer W on the surface 51 and keeps travelingvertically downward into the chuck body 62. The end effector mustretract from the chuck 50 to allow the chuck to spin the wafer W. If thearms 202 and 204 cannot move away from the chuck body 62 in thedirection 232, the end effector would not be able to retract from thechuck 50 in the direction 234. In one embodiment, each recessed surfacetravels completely through the chuck body 62 such that the end effectormay effectively pass through the bottom surface of the chuck body 62 andthen retract in the direction 234 away from the chuck 50.

Alternately, the chuck body 62 includes a first horizontal slot 60 and asecond horizontal slot 63 each located at a predetermined elevationbelow the surface 51. The slots allows the end effector to lower thearms 202 and 204 to an elevation aligned with the slots 60 and 63, andsubsequently retract in the direction 234 away from the chuck 50 throughthe slots 60 and 63. Arm 202 passes through the chuck body 62 within theslot 60 and the arm 204 passes through the chuck body 62 within the slot63. If the end effector 200 includes a third arm 222 (as shown in FIG.3), the chuck body 62 includes a fifth recessed surface 65 toaccommodate the third arm 222. In operation after the end effector 200places the wafer W on the surface 51 the end effector continues totravel vertical downward and the arm 222 will pass through the body 62within the recessed surface 65. Each recessed surface in the chuck body62 takes away a small amount of the support surface 51. However, thereduction in the support surface 51 due to the recessed surfaces isminimal.

In semiconductor processing, wafers often have a starting thickness of0.7 mm-1.0 mm. The wafers are then thinned to a thickness of less than0.3 mm at some intermediate stage of the total manufacturing processsequence. The thinned wafer is very flexible and fragile, and thehistorical methods of wafer edge support in a container as well as theconventional edge gripping methods, are not adequate.

Each storage shelf supports a wafer at multiple points. In particular,each storage shelf preferably supports a wafer by at least three contactpoints or support pads. In one embodiment, a storage shelf, whichcomprises two tines 106, includes a single support pad on each tine 106(e.g., support pad 110) and a support pad located on each base member104 (e.g., support pad 108)—all at substantially the same elevation inorder to support a wafer in a horizontal orientation. In anotherembodiment, each tine 106 includes an additional support pad (e.g.,support pad 116) to provide additional support. Of course, each tine 106and/or base member 104 may include additional support pads. The numberand geometry of additional support pads for both the end effector andthe storage shelves is limited only by the requirement for the endeffector to interact with each tine 106.

FIG. 9 illustrates one embodiment of a wafer support structure 202within a conventional FOUP 10. The FOUP 10 includes a housing or shell12 and a FOUP door 14 that mechanically couples with the FOUP shell 12.The housing 12, which includes a top 18, a back 20, a first side 22, asecond side 24 and a bottom 26, defines an enclosure 28.

In this embodiment, the support structures 202 are affixed to the top 18and bottom 26 of the FOUP shell 12. For example, the top end 203 of eachsupport structure 202 is affixed to the top 18 of the FOUP shell 12 bythree fixtures 205. The bottom end (not shown) of the support structure202 is fixed to the bottom 26 of the FOUP shell 12. It is also withinthe scope of the present disclosure for the support structures 202 to beaffixed to either the top 18 or the bottom 26 of the FOUP shell 12, orbe affixed to the FOUP shell 12 by other methods. Each support structure202 may also be molded with the FOUP shell 12. For example, each basemember 204 may be molded into the back 20 of the FOUP shell 12, or anyof the other surfaces of the FOUP shell 12 (e.g., top 18, bottom 26,first side 22, second side 24, etc.). In another embodiment, the supportstructure 202 may not include a base member 204. Instead, each storageshelf comprises one or more tines 206; each affixed or molded into theFOUP shell 12. For example, the proximal end 214 of each tine 206 mayinclude a pair of tabs that lock into a pair of slots located in theback 20 of the FOUP shell 12. FIG. 9 illustrates that the two supportstructures 202 comprise two separate structures. However, any portion ofthe support structures 202, such as the base members 204 and/or tines206, may comprise a single piece of material.

FIG. 9 illustrates one embodiment of a storage shelf, comprising a pairof tines 206, for exemplary purposes. Each tine 206 extends or projectsfrom the base member 204. The tine 206 includes a first end or proximalend 214 and a second end or distal end 216. The combination of the twotines 206 and the base members 204 support a single wafer W with sixsupport pads—two support pads 208, two support pads 210 and two supportpads 212. The support pad 210 is located at or near the distal end 216of each tine 206. The other four support pads 208 and 212 may be locatedon either the proximal end 214 of the tine 206 or the base members 204,or a combination of the two. It is within the scope of the presentdisclosure for other portions of the tine 206 to contact the wafer W orfor the support pads to be located in other positions.

FIG. 9 illustrates that the wafer's peripheral edge P, and a portion ofthe wafer W, overhangs or extends beyond the outer edge 207 of each tine206 between the support pads 210 and 212—while the wafer W is seated onthe storage shelf. As discussed above, this overhanging portion of thewafer W is referred to as the “grip” or “access” area that may beengaged by an end effector while the wafer W is seated in the FOUP 10.

FIG. 10 illustrates an end effector 700 inserted into the FOUP 10. Theend effector 700 includes a body 701, a first arm 702 and a second arm704. The body 701 may be connected to, by way of example only, a roboticarm for moving the end effector body 701 through any number of movements(e.g., six degrees of freedom motion). The first arm 702 has a proximalend 706 and a distal end 708. The second arm 704 includes a proximal end707 and a distal end 709.

The FIG. 10 embodiment of the end effector 700 includes two support padson each arm. The first arm 702 includes a support pad 710 located a theproximal end 706 and a second support pad 712 located at the distal end708. The second arm 704 includes a support pad 714 located the proximalend 707 and a support pad 716 located at the distal end 709. Each armmay include any number of support pads, and each support pad may belocated anywhere along the end effector's arms. It is preferable thatthe support pads do not interfere with the support structure 202. FIG.10 illustrates each support pad 710-716 as a passive pad. Alternately,each support pad 710-716 may comprise an active pad similar to the endeffector embodiments shown in FIGS. 4-8.

When the end effector 700 is placed into the FOUP enclosure 28, the arms702 and 704 contour around the wafer's peripheral edge P—as shown inFIG. 10. In a preferred embodiment, the distance between the wafer'speripheral edge P and each side of the FOUP shell 12, such as the firstside 22 and the second side 24, is large enough so that the arms 702 and704 of the end effector 700 may travel vertically within the enclosure28 without contacting any part of the support structure 202 or the waferW or the FOUP shell 12. It is also within the scope of the presentdisclosure for this distance to be minimal (as shown in FIG. 10) suchthat arms 702 and 704 of the end effector 700 may not travel verticallywithin the enclosure 28 without contacting any part of the supportstructure 202 or the wafer W. Thus, after setting a wafer on a storageshelf, the end effector 700 would have to travel out of the enclosure,and raise/lower to another elevation before the end effector 700 can beinserted back into the enclosure 28.

Unlike a conventional end effector, the arms 702 and 704 preferably donot travel under a wafer in order to place the contact pads 710-716under a wafer or lift a wafer from a storage shelf. Maintaining the arms702 and 704 on the outside of the wafer W eliminates the possibilitythat either of the arms 702 or 704 will contact and/or damage thesurface of a wafer seated in the FOUP 10. The shape of the arms 702 and704 shown in FIG. 10 is for exemplary purposes only.

The arms 702 and 704 may comprise other shapes and/or configurations.

The arms 702 and 704 of the end effector 700 also preferably contouraround each tine 206. If the support pads 710-716 are active pads (e.g.,able to move towards/away from the wafer's peripheral edge P), the endeffector 700 may be placed into the FOUP enclosure 28 at any height andsubsequently move vertically to another elevation within the FOUP 10without having to first withdraw from the FOUP enclosure 28. With thesupport pads retracted, the end effector 700 may travel to its desiredposition. Once the end effector 700 reaches a desired location, thesupport pads 710-716 extend towards the wafer until a portion of eachsupport pad 710-716 is located below the wafer W. This way, the wafer Wwill be supported (preferably in a horizontal orientation) when the endeffector 700 lifts the wafer W off the tines 206 or storage shelf andremoves the wafer W from the FOUP 10.

It should be appreciated that the above-described tine systems and endeffectors are for explanatory purposes only and that the invention isnot limited thereby. Having thus described a preferred embodiment of atine system and end effector, it should be apparent to those skilled inthe art that certain advantages of the within system have been achieved.It should also be appreciated that various modifications, adaptations,and alternative embodiments thereof may be made within the scope andspirit of the present disclosure. For example, the storage shelves andend effector have been illustrated in a semiconductor fabricationfacility, but it should be apparent that many of the inventive conceptsdescribed above would be equally applicable to be used in connectionwith other non-semiconductor manufacturing applications. It should beapparent that the storage shelves are also not limited to workpiececarriers.

The invention claimed is:
 1. An end effector comprising: a body; a first arm attached to and extending from the body in a direction, a second arm attached to and extending from the body in the direction; each of the first and second arms having a proximal end closer to the body than a distal end; a distal support pad extending from each of the first and second arms towards the other arm, the distal support pad located closer to the distal end than to the proximal end, wherein the distal support pads are located in a retracted position to facilitate travel of the first and second arms vertically within an enclosure of a container, wherein the distal support pads are located in a support position to support a workpiece when present in the container, wherein the first and second arms are configured to move closer or away from each other, wherein in the retracted position, the distal support pads are away from each other to not support the workpiece, and in the support position, the distal support pads are closer to each other to support the workpiece when present; and a finger extending from the body in the direction in which the first and second arms extend, wherein the finger extends between the first and second arms to be below a lower surface of the workpiece when present, wherein the finger has a finger support pad that extends from a top surface of the finger to support the workpiece when present.
 2. The end effector of claim 1, wherein each of the first and second arms is curved between the proximal end and the distal end, wherein the body has a portion that is straight.
 3. The end effector of claim 1, wherein the finger is straight and is located between the first and second arms, wherein the finger support pad extends from the finger towards the workpiece when present.
 4. The end effector of claim 3, wherein the finger has a shorter length in the direction compared to a length of each of the first and second arms in the direction.
 5. The end effector of claim 1, further comprising: a first additional support pad extending from the first arm towards the second arm and located between the proximal end of the first arm and the distal end of the first arm; a second additional support pad extending from the second arm towards the first arm and located between the proximal end of the second arm and the distal end of the second arm, wherein the first and second additional support pads are configured to support the workpiece when present, wherein the proximal end of each of the first and second arms is contiguous with the body.
 6. The end effector of claim 5, wherein each of the distal support pads has a contact surface that extends in a horizontal direction and a backstop that extends in a vertical direction with respect to the contact surface of the distal support pad, wherein each of the first and second additional support pads has a contact surface that extends in the horizontal direction and a backstop that extends in the vertical direction with respect to each respective contact surface of the first and second additional support pads.
 7. The end effector of claim 6, wherein each backstop of the distal support pads is configured to extend in the vertical direction to prevent the workpiece from sliding from each respective contact surface of the distal support pads, wherein each backstop of the first and second additional support pads is configured to extend in the vertical direction to prevent the workpiece from sliding from each respective contact surface of the first and second additional support pads.
 8. A system comprising: a container having a plurality of base members, the container further having a plurality of tines that extend from the base members into an interior space of the container; and an end effector including: a body; a first arm attached to and extending from the body in a direction, a second arm attached to and extending from the body in the direction; each of the first and second arms having a proximal end closer to the body than a distal end; a distal support pad extending from each of the first and second arms towards the other arm, the distal support pad located closer to the distal end than to the proximal end, wherein the distal support pads are located in a retracted position to facilitate travel of the first and second arms vertically within the interior space of the container, wherein the distal support pads are located in a support position to support a workpiece when present in the container, wherein in the retracted position, the distal support pads are away from each other to not support the workpiece, and in the support position, the distal support pads are closer to each other to support the workpiece when present; and a finger extending from the body in the direction in which the first and second arms extend, wherein the finger extends between the first and second arms to be below a lower surface of the workpiece when present, wherein the finger has a finger support pad that extends from a top surface of the finger to support the workpiece when present.
 9. The system of claim 8, wherein each of the first and second arms is curved between the proximal end and the distal end, wherein the body has a portion that is straight.
 10. The system of claim 8, wherein the finger is straight and is located between the first and second arms, wherein the finger support pad extends from the finger towards the workpiece when present.
 11. The system of claim 10, wherein the finger has a shorter length in the direction compared to a length of each of the first and second arms in the direction.
 12. The system of claim 8, wherein the end effector comprises: a first additional support pad extending from the first arm towards the second arm and located between the proximal end of the first arm and the distal end of the first arm; a second additional support pad extending from the second arm towards the first arm and located between the proximal end of the second arm and the distal end of the second arm, wherein the first and second additional support pads are configured to support the workpiece when present, wherein the proximal end of each of the first and second arms is contiguous with the body.
 13. The system of claim 12, wherein each of the distal support pads has a contact surface that extends in a horizontal direction and a backstop that extends in a vertical direction with respect to the contact surface of the distal pad, wherein each of the first and second additional support pads has a contact surface that extends in the horizontal direction and a backstop that extends in the vertical direction with respect to each respective contact surface of the first and second additional support pads.
 14. The system of claim 13, wherein each backstop of the distal support pads is configured to extend in the vertical direction to prevent the workpiece from sliding from each respective contact surface of the distal support pads, wherein each backstop of the additional support pads is configured to extend in the vertical direction to prevent the workpiece from sliding from the each respective contact surface of the first and second additional support pads.
 15. An end effector comprising: a body having a length that extends in a direction; a first arm attached to and extending from the body in the direction, a second arm attached to and extending from the body in the direction; each of the first and second arms having a proximal end closer to the body than a distal end; a distal support pad extending from each of the first and second arms towards the other arm, the distal support pad located closer to the distal end than to the proximal end, wherein the distal support pads are located in a retracted position to facilitate travel of the first and second arms vertically within an enclosure of a container, wherein the distal support pads are located in a support position to support a workpiece when present in the container, wherein in the retracted position, the distal support pads are away from each other to not support the workpiece, and in the support position, the distal support pads are closer to each other to support the workpiece when present; and a finger extending from the body in the direction in which the first and second arms extend, wherein the finger extends between the first and second arms to be below a lower surface of the workpiece when present, wherein the finger has a contact surface that extends from a top surface of the finger to support the workpiece when present.
 16. The end effector of claim 15, wherein each of the first and second arms is curved between the proximal end and the distal end, wherein the body has a portion that is straight.
 17. The end effector of claim 15, wherein the finger is straight and is located between the first and second arms, when the contact surface extends from the finger towards the workpiece when present.
 18. The end effector of claim 17, wherein the finger has a shorter length in the direction compared to a length of each of the first and second arms in the direction.
 19. The end effector of claim 15, further comprising: a first additional support pad extending from the first arm towards the second arm and located between the proximal end of the first arm and the distal end of the first arm; a second additional support pad extending from the second arm towards the first arm and located between the proximal end of the second arm and the distal end of the second arm, wherein the first and second additional support pads are configured to support the workpiece when present, wherein the proximal end of each of the first and second arms is contiguous with the body.
 20. The end effector of claim 19, wherein each of the distal support pads has a contact surface that extends in a horizontal direction and a backstop that extends in a vertical direction with respect to the contact surface of the distal pad, wherein each of the first and second additional support pads has a contact surface that extends in the horizontal direction and a backstop that extends in the vertical direction with respect to each respective contact surface of the first and second additional support pads, wherein each backstop of the distal support pads is configured to extend in the vertical direction to prevent the workpiece from sliding from each respective contact surface of the distal support pads, wherein each backstop of the first and second additional support pads is configured to extend in the vertical direction to prevent the workpiece from sliding from the each respective contact surface of the first and second additional support pads. 